Electrical conductor terminating arrangements

ABSTRACT

An electrical conductor terminating arrangement such as an electrical connector includes a contact-making element which makes good contact with an electrical conductor in response to axial pressure displacement over the contact-making element of a displaceable element to exert a radial force on the contact-making element and to co-operate therewith for providing ongoing pressure engagement between the contact-making element and the electrical conductor without the need for the continuance of axial pressure on the displaceable element after a predetermined axial displacement of the displaceable element.

This invention relates to electrical conductor terminating arrangementswhich are especially, but not exclusively, applicable to the terminationof electrical conductors in electrical connectors of the coaxial type.

The invention is especially directed to an improved conductorterminating arrangement in a coaxial connector of the kind facilitatingthe ready and effective connection of the usual central conductor of anincoming coaxial cable to contact means (e.g. pin contact) of theconnector without the need for crimping and/or other tools.

A coaxial connector is known from U.S. Pat. No. 3,761,870 in which thecentral conductor is secured to a clamping member by the action of anaxial force which is exerted upon assembly of the connector by means ofa nut which is threadably connected to the connector body,. The nutcauses a clamping member to be axially displaced which clamping memberhas a bevelled end surface which cooperates with the periphery of amushroom shaped resilient dielectric element which has a through channelthat fits over the clamping member. The axial force causes radial inwarddepression on the clamping member to effect clamping of the conductor.When the axial pressure is removed, for example upon the disassembly ofthe connector, the radially inward depression is terminated and theelectrical and mechanical integrity between the clamping member and theconductor is no longer maintained and they are easily separable.

Another coaxial connector is known from U.S. Pat. No. 3,847,463 in whichthe central conductor is secured within a collet having a bevelled end.This is effected by cooperation with a collet closer which has abevelled recess, conforming with the bevel of the collet, the twobevelled surfaces cooperating upon relative axial displacement intoengagement to clamp the conductor. The relative axial displacement iseffected during assembly of the connector by screwing action between acable nut and an outer conductor. The clamping action is dependent uponthe axial force exerted by the relative axial displacement and removalof that axial force by unscrewing of the cable nut permits theseparation of the collet and collet closer thereby failing to maintainelectrical and mechanical integrity between the collet and theconductor.

The present invention seeks to provide a connector which electrical andmechanical integrity is maintained when an axial clamping force isremoved so that the connector can be disassembled without that integritybeing sacrificed.

According to the present invention there is provided an electricalconductor terminating arrangement, comprising an electrically conductivecontact-making means for receiving a conductor, an axially displaceablemeans which when displaced over the contact making means in a directionaxially of the contact making means exerts a radial force on the contactmaking means to secure the conductor by pressure engagement,characterised in that the contact, making means and axially displaceablemeans are adapted to ensure retentive mutual engagement therebetweenwhen the axially displaceable means is displaced axially over thecontact making means to provide ongoing radial pressure engagementbetween the contact making means and the electrical conductor in orderto maintain electrical and mechanical integrity therebetween without theneed for continuance of axial pressure on the axially displaceablemeans.

By ensuring that the axially displaceable means and contact making meansare mutually retentively secured after axial displacement then theelectrical and mechanical integrity of the connection of the contactmeans to the conductor is ensured even when the connector isdisassembled.

In carrying out the present invention the displaceable means maycomprise a resilient or non-resilient sleeve member which when displacedaxially exerts an inward radial force on the contact-making meanslocated within the sleeve member and which co-operates with thecontact-making means positioned over the electrical conductor to providethe aforesaid ongoing pressure engagement with the conductor. Aresilient sleeve member may be provided by a split metal ring or acontinuous ring of resilient plastics material whereas a continuousmetal ring may comprise a non-resilient sleeve member.

The contact-making means of the conductor terminating arrangement maycomprise a compressible clamping element adapted to fit over theelectrical conductor.

The compressible clamping element may comprise a split tubular metalpart into one end of which the conductor extends and which is adapted tobe radially compressed by the contact-making means to make goodelectrical contact with the conductor. The split tubular metal part maybe formed integrally with contact means (e.g. pin contact) of theterminating arrangement provided at the end thereof remote from the endat which the conductor enters the tubular compressible clamping element.

To positively ensure good electrical contact between the compressibleclamping element and the electrical conductor, the actual conductorclamping region of the element may be screw-threaded or otherwiseconfigured to bite into the outer surface of the electrical conductor asclamping takes place.

The split tubular clamping element may, for example, be provided withradial slots which have a width less than the diameter of the conductorand which present at the periphery of a central passage in the elementfor slidingly receiving the conductor, sharp edges to bite into theouter surface of he conductor to make good electrical contact therewithwhen the clamping element is compressed. Four such radial slots may beprovided to afford a passageway of cruciform configuration but othermulti-slot constructions are also contemplated.

To accommodate conductors of different sizes the nubular clampingelement may be stepped on its inner surface.

The split tubular clamping element may be of relatively large diameterand connected with the contact means of the terminating arrangement by asplit frusto-conical section which facilitates smooth and easytransitional displacement of an associated resilient sleeve member fromthe conical surface thereof to the outer periphery of the clampingelement in order to compress the tubular element radially inwards as theresilient sleeve member is displaced axially over the split tubularelement.

In accordance with one especially contemplated application of thepresent invention, a conductor terminating arrangement of the foregoingconstruction as broadly conceived is provided as part of a coaxialconnector comprising a tubular body structure having an axiallyextending bore therein for receiving an incoming coaxial cable and foraccommodating the electrically conductive contact-making means of theterminating arrangement located adjacent a part of the cable within thetubular body structure and electrically coupled with connector contactmeans (e.g. pin contact), the displaceable means of the arrangement, inresponse to the predetermined axial displacement thereof exerting aradial force on the contact-making means with which it co-operates toprovide ongoing pressure engagement between the contact-making means andthe central conductor of the coaxial cable to ensure good electricalcontact therebetween without the need for the continuance of any axiallyapplied force to the displaceable means.

The resilient or non-resilient sleeve member may form part of theaxially displaceable means which also comprises a tubular insulatingmember at least partly accommodated within the axially extending bore ofthe tubular body structure of the connector at the contact means end ofthe connector, the sleeve member being engaged by or being attached toor formed integrally with the tubular insulating member.

Displacement of the tubular insulating member may be arrested by theabutment of an end portion of the member with shoulder means of acup-shaped insulating stop member located within the bore of the tubularmember and having a tapered opening therethrough for the passage of thecentral conductor of the coaxial cable.

The tubular insulating member received by the axially extending bore ofthe tubular body structure of the connector may, in accordance with ourco-pending British patent application No. 9223824.5, be adapted to makea first snap engagement with another connector part whereby theconnector conductor clamping or contacting-making component part is heldin a pre-conductor clamping or connecting state. The tubular insulatingmember may also be adapted to be moved further to a position at which itmakes a second snap engagement with a connector part when the clampingor contact-making part makes good electrical contact with the centralconductor.

The provision of such a pre-conductor clamping and pre-conductor contactassembled state of the connector in which connector component parts arecontained in situ enables the connector to be handled/transported and/ordelivered without the risk of parts becoming detached or lost.

For the purpose of gripping an incoming coaxial cable at the end of theconnector where the coaxial cable enters, a suitable strain-reliefarrangement may be provided.

The strain relief facility may be provided by sliding the end of theconnector remote from the contact between the metal braiding of thecable and the underlying cable insulation and then crimping a metalferrule down on to the braiding.

By way of example various embodiments of the present invention will nowbe described with reference to the accompanying drawings in which:

FIG. 1 shows a longitudinal cross-sectional view of a coaxial cableconnector comprising a conductor terminating arrangement in accordancewith the present invention;

FIG. 2 shows an exploded view of the coaxial cable connector of FIG. 1with small modifications;

FIG. 2a shows an enlarge detail of FIG. 2; and,

FIGS. 3a, 3b and 3c show different steps in the connection of anincoming cable to the connector of FIG. 1.

Referring now to FIGS. 1 and 2 of the drawings, the embodiment depictedtherein constitutes a preferred construction which provides inter alia apre-conductor clamping assembled state of the connector.

The tubular body structure of the coaxial connector comprises twogenerally cylindrical metal parts 22 and 23, the body part 22 having anexternally-threaded portion 24 which, as facilitated by the integral nuhead 25, can be screwed into an internally-threaded portion of the bodypart 23. The body part 22 includes a cylindrical cavity 26 whichslidingly receives a hollow cylindrical latching member 27 ofelectrically insulating material. The end of the latching member 27which engages the base of the cavity 26 is provided with a conicalrecess 28 against the surface of which the end of the dielectric layerof an incoming coaxial cable to the connector will abut, as will laterbe apparent. The right-hand end of the latching member 27 is providedwith a radially inwardly extending lip or projection 29.

The latching member 27 is adapted to receive the end of a split radiallycompressible metal clamping collet 31 of the conductor terminatingarrangement which, in the present embodiment is formed integrally with acontact 32 (e.g. pin contact) of the connector connected to the collet31 by a split conical section 33. The internal periphery of the clampingcollet may be threaded or provided with serrations or surfaceirregularities or otherwise configured in order to bite into the outersurface of the single or stranded central conductor of the coaxial cableduring the conductor clamping operation in the present embodiment themetal clamping collet 31 of the terminating arrangement, as can best beseen from FIG. 2a of the drawings, is split axially by means of fourradial slots 34 which define a cruciform passageway extending axiallythrough the collet and providing four axially extending sharp corners oredges 34a towards the centre of the passageway where clamping of acentral conductor 44 of the coaxial cable takes place. The width of theradial slots 34 will be less than the diameter of the central conductorbut the central passage or region of the cruciform passageway will besufficiently large to slidingly receive the central conductor 44 beforeradial compression of the collet 31 takes place to effect clamping ofthe conductor and termination of the latter in the connector. Duringsuch conductor clamping the axially extending sharp edges 34a of timesit of the collet 31 will bite into the conductor 44 in order to ensuregood electrical contact therewith. Thus, the collet 31 serves as acontact making means for contacting the conductor 44 as a result of theradial force on the contact making means 31 by axial displacement of theclamping ring, or clamping means 35. As will readily be apparent, othermulti-slot collet constructions could alternatively be provided toachieve a similar result. A six slot collet construction is alsoespecially contemplated.

A resilient split metal sleeve member, or clamping ring 35 forming partof axially displaceable means and corresponding to the clamping ring 35in FIG. 1 is provided for co-operating with the collet 31 to effectradial compression thereof. To achieve such compression, a tubularaxially-displaceable member 36 of insulating material also forming partof the displaceable means is provided. The displaceable member 36 isslidably received in a through bore 37 of the body part 23. When the twobody parts 22 and 23 are secured together with the collet 31 theco-operating clamping ring 35 is located within the internal cylindricalcavity of the body structure, and the member 36 can readily be displacedaxially. Axial displacement is achieved simply by exerting fingerpressure on the right-hand end of the clamping member, as viewed in thedrawing, so that the radially flexible slotted end of the member 36defined by slots 38 first makes snap engagement with the tubularlatching member 27. Such first engagement is by the engagement or theinternal lip or projection 29 on the member 27 with an externalcircumferential groove 39 in the slotted end of the displaceable member36. It will be appreciated that the latching member 27 could be possiblybe slotted, in which case the slots 38 in the member 36 could bedispensed with. As will readily be appreciated from FIG. 1 of thedrawings which shows the connector in an assembled state prior toclamping of the central cable conductor, component parts of theconnector are securely held in situ by the initial latching arrangementprovided between the members 27 and 36 with the lip 29 of member 27engaging groove 39 in the member 36. Such an arrangement importantlyenables connectors to be handled and/or transported/delivered inreadiness for cable connection and conductor clamping without the riskof connector parts becoming detached or lost.

In order to connect the connector to an incoming coaxial cable, as shownat 40 in FIG. 3a of the drawings, the usual outer insulation sleeve 41will be cut back, as shown, to expose a suitable length of an underlyingmetal braided screen 42. The metal braid will then be stripped back, asshown, over a requisite length to leave a length of extruded dielectricinsulation 43 exposed. This dielectric will then be cut back to leave alength of bared central conductor 44. The cable end will then beinserted through a metal crimping ferrule, shown at 45 in FIGS. 2 and3b, and then into the cable receiving end of the body part 22 which isalready screwed to the body part 23 in the pre-conductor clampingassembled state of the connector shown in FIG. 1. The body part 22 has atubular extension 46 which may have circumferential ridges 47 so that asthe cable moves into the-interior of the connector the ridged extension46 will be urged between the dielectric layer 43 and the metal braidingsleeve 42 of the cable, as shown in FIG. 3b, whilst the bared end 44 ofthe central conductor will move into and along the central passage ofthe clamping collet 31 as indicated in FIG. 2a of the drawings, untilthe forward end of the exposed dielectric material 43 abuts against heconical surface of the recess 28 provided in the latching member 27.

To effect clamping of the collet 31 to the central conductor 44 of theincoming cable 40 and thereby effect termination of the conductor 44 inthe connector, the axially displaceable member 36 is simply pressed fromits initial pre-clamping latched position further into the bore 37, as aresult of which the clamping ring 35 of the terminating arrangement willbe forced by the displacement member 36 over the cylindrical surface ofthe split collet 31 which is accordingly compressed radially inwards sothat the inner axially extending sharp edges 34a, as shown in FIG. 2a,bite into the outer surface of the single or stranded central conductorin order to make good electrical contact therewith. When sufficientclamping force has been exerted on the collet 31 by movement of theclamping ring 35, the displaceable member 36 makes a second and finalsnap engagement with the latching member 27 by the engagement of asecond circumferential groove 48 in the member 36 with the inturned lipor projection 29 on the latching member 27. In this position of thedisplaceable member 36 the components of the connector are in theconductor clamped assembled state with the resilient split clamping ring35 co-operating with the split collet 31 to provide ongoing pressureengagement between the collet and the central conductor. No continuingaxial pressure needs to be applied to the displaceable member. In thisclamped conductor state of the connector the cable may be pulled tocarry out a tensile test for ensuring that effective clamping of thecentral conductor has been achieved.

Although in the embodiment described with reference to FIGS. 1 to 3 theclamping ring 35 comprises a resilient split metal ring whichco-operates with the clamping element 31 to provide ongoing pressureengagement with the central conductor 44, it will be appreciated thatthe clamping ring 35 could be replaced by a non-resilient (continuous)sleeve member which co-operates with resilient contact-making means overwhich such non-resilent sleeve member fits to provide the ongoingpressure engagement between the contact-making means and the centralconductor of the co-axial cable.

It is contemplated that the members 27 and 36 could be composed of atransparent insulating material which would enable a conductor clampconnection to be viewed after unscrewing the two body parts.

In order to complete the strain relief connection between the incomingcable 40 and the connector, the metal ferrule 45 may be positioned overthe metal braiding overlying the tubular ridged extension 46, as can beseen in FIG. 3b of the drawings, and then crimped down on to thebraiding, as shown in FIG. 3c.

To enable the connector to be panel mounted, a radially collapsible ring49 may be fitted in a groove of the body part 23. The configuration ofthe ring allows the contact end of the connector to be inserted into apanel aperture after which the ring restores to hold the connector inposition.

The tubular insulating member 36 and the bore 37 of the tubular bodystructure may be provided with grooves and/or projections whichcooperate to lock the tubular insulating member in position within thebore of the body structure as clamping takes place.

We claim:
 1. An electrical conductor terminating arrangement, comprisingan electrically conductive contact-making means (31) for receiving andmaking electrical contact with an electrical conductor, an axiallydisplaceable clamping means (35) which when displaced over the contactmaking means in a direction axially of the contact making means (31)exerts a radial force on the contact making means to secure a conductorwhen installed by pressure engagement, characterized in that the contactmaking means (31) and axially displaceable means (35) are adapted toensure retentive mutual engagement therebetween when the axiallydisplaceable means is displaced axially over the contact making means toprovide ongoing radial pressure engagement between the contact makingmeans (31) and the electrical conductor (44) when installed in order tomaintain electrical and mechanical integrity therebetween without theneed for continuance of axial pressure on the axially displaceable means(35).
 2. An electrical conductor terminating arrangement as claimed inclaim 1, characterized in that the axially displaceable clamping means(35) comprises a sleeve member which exerts an inward radial force onsaid contact-making means (31) located within it and which co-operateswith said contact-making means to provide ongoing pressure engagement ofthe contact-making means with the conductor when installed.
 3. Anelectrical conductor terminating arrangement as claimed in claim 2,characterized in that the sleeve member (35) is resiliently compressibleand is provided by a split ring.
 4. An electrical conductor terminatingarrangement as claimed in claim 2, characterized in that the sleevemember (35) comprises a continuous metal ring.
 5. An electricalconductor terminating arrangement as claimed in any one of the precedingclaims, characterized in that the contact-making means (31) comprises acollet adapted to fit over the conductor (44) and to be subjected to aradial compressive force by the clamping means (35) in order to causethe collet to clamp down on the conductor.
 6. An electrical conductorterminating arrangement as claimed in claim 5, characterized in that thecollet comprises a split tubular metal part which has aconductor-receiving end, with said tubular metal part adapted to beradially inwardly compressed to make good electrical contact with theconductor.
 7. An electrical conductor terminating arrangement as claimedin claim 5, characterized in that said terminating arrangement includesa pin contact and in which the split tubular metal part (31) is formedintegrally with said pin contact at an end of the split tubular metalpart remote from the conductive compressible clamping means.
 8. Anelectrical conductor terminating arrangement as claimed in claim 5,characterized in that said collet is configured to bite into the outersurface of the conductor as clamping takes place.
 9. An electricalconductor terminating arrangement as claimed in claim 5, characterizedin that the collet is provided with radial slots (34) which have a widthless than the diameter of the conductor and which form tines with sharpedges (34a) to bite into the outer surface of the conductor to make goodcontact therewith when the clamping element is compressed.
 10. Anelectrical conductor terminating arrangement as claimed in claim 9,characterized in that four slots (34) are provided in the collet.
 11. Anelectrical conductor terminating arrangement as claimed in claim 7,characterized in that the clamping means comprises a sleeve member andthe collet has a split frusto-conical section (33) that is engaged bysaid sleeve.
 12. An electrical conductor terminating arrangement asclaimed in claim 5, characterized in that the clamping means is steppedto accommodate conductors of different diameters.
 13. A coaxialconnector comprising a tubular body structure (23) having an axiallyextending bore therein for receiving an incoming coaxial cable that hasa central cable conductor, including a conductor terminating arrangementcomprising:a collet with tines that can engage said central conductorand a sleeve member which is axially displaceable to compress said tinesaround said conductor to provide ongoing pressure engagement betweensaid collet and the central conductor (44) of the coaxial cable.
 14. Acoaxial connector as claimed in claim 13, including:an axiallydisplaceable tubular insulating member (36) at least partly accommodatedwithin said axially extending bore of the tubular body structure (23),and in which the sleeve member is axially movable by the tubularinsulating member.
 15. A coaxial connector as claimed in claim 14,including a cup-shaped stop member, and in which axial movement of thetubular insulating member (36) during clamping is arrested by theengagement thereof with said stop member (27), with said stop memberaccommodated in the bore (37) of the tubular body structure and intowhich the sleeve member fits during conductor clamping.
 16. A coaxialconnector as claimed in claim 14, characterized in that the tubularinsulating member (36) and the bore of the tubular body structure areprovided, one with at least one projection and the other with at leastone groove, which co-operate to lock the tubular insulating member inposition within the bore of the body structure as conductor clampingtakes place.
 17. A co-axial connector as claimed in claim 13,characterized in that the tubular body structure comprises two parts(22, 23) which are threadingly connected together.
 18. A coaxialconnector as claimed in claim 17, characterized in that at least onepart of the connector is composed of transparent insulating material toallow the condition of the connector to be inspected followingseparation of the body structure parts (22, 23).